We have begun scrutinizing the datasets for NATL TS, and I would appreciate any
comments/advice that you have on discrepencies that we have found in the HURDAT
data set. The attached file noting discrepancies and the message below was
prepared by two Georgia Tech students, James Belanger and Mark Jelinek. We
have read the documentation and understand that this is a work in progress.
We note only errors of internal inconsistency within the data sets.

These internal inconsistencies need to be cleaned up. Ideally this would be
done by the group that generated the data set. If there are insufficient
resources to do this in the short term, we will either fix the discrepancies
based upon any advice that we receive, and/or assign error bars to particular
storms associated with the discrepancies in the data set. We prefer that
others modify the data set so that we can use an "off the shelf" data set
(so that we are not accused of "cooking" the data set in case we come up with
any controversial findings :)

Comments from the best tracks committee and/or other users of the data set
would be greatly appreciated. Thanks.

Judy

Notes regarding the attached xcel spreadsheet:

"The purpose of this evaluation was to identify both obvious and potential
errors related to the three versions of the HURDAT data files available at

1. The analysis first identified the discrepancies between the 'Tab
Delimited' version and the 'Easy to Read' version then between those two
versions and the 'Original' version
2. Then apparent discrepancies between the 'Best Track' portion of the data
and the landfall designation information were identified"

Each worksheet title is an indicator as to the analysis contained within
"The analysis did not review and/or attempt to clarify:

Any potential discrepancies with the storm speed/direction or maximum winds
expressed in miles and kilometers per hour that are calculated and provided in
both the 'Easy to Read' and 'Tab Delimited' versions from the components in the
'Original' version of the data

Any discrepancies between the 'Center Fix' and 'Metadata' portion of the
reanalysis and the 'Original' data file

Any concerns about terminology used in making the landfall designations
contained in the 'Original' data file"

It appears that a number of comments attached to your note deal with
differences found between HURDAT and two other derived versions that appear on
the AOML/HRD website.

While clearly they should be consistent, it appears that a programming
oversight within that organization created most of the inconsistencies, hence
our recommendation that only HURDAT be used for analysis. It is our
understanding that these derived versions were created for the purpose of
making the dataset more ‘readable’ rather as an alternative source for
scientific investigation. Chris Landsea has informed me that these errors
have now been been corrected and reposted to the AOML/HRD website.

This is not to say that HURDAT itself is without flaws, and we appreciate your
efforts in uncovering inconsistencies. We continue to find and correct
errors. I believe you are aware of the ongoing re-analysis effort being
conducted by Chris Landsea that was specifically designed to screen for errors
and apply current understanding to the dataset. As of this writing, the NHC
Best-Track Change Committee (BTCC) is evaluating the submission of Landsea et
al. for 1915-1923. I can attest that this is quite a labor-intensive process
both for the re-analysis team and the BTCC. In addition, any changes made to
U.S. landfalling category 4 or 5 hurricanes must be submitted for outside
review. The BTCC strives to consider all available sources before making a
decision. During the reevaluation of H. Andrew, for example, the BTCC hosted a
multi-day workshop to hear a variety of opinion. Individual cases can be very
difficult to decide. However, progress is being made and the official version
of HURDAT now reflects changes accepted by the BTCC for the period 1851-1914,
and H. Andrew, 1992.

As part of this process, we require that data, discussion, and rationale be
provided for any changes. The resulting 'metadata' appears on the re-analysis
webpage. Please note that inspection of the metadata, in particular with
regard to the winds at the time of landfall, can resolve many of these
apparent discrepancies.

With regard to the "Best Track vs. Landfall" comments, you have indeed found
some important inconsistencies for the period of 1915 to 2002. We are aware
of many of these, and in fact they have provided the impetus for the
reanalysis. As such, they will be dealt with sequentially within the
reanalysis. Again, if you have raw observations, suggested HURDAT changes,
and a discussion on how to resolve these inconsistencies, please feel free to
submit these directly to the reanalysis committee.

However, out-and-out errors are a different matter and can be corrected fairly
quickly. Concerning the comments for 1851 to 1914, four of these were indeed
correct and changes have been to made accordingly to HURDAT for these systems:
1874/07, 1878/05, 1880/11, and 1893/04. However, for the remainder no changes
were needed. We would encourage your students to read through both the
Metadata documentation on these individual systems:

to see why the tropical storms and hurricanes are categorized as they
currently are. Also note that what appear to be errors in the landfall
designation are very frequently artifacts of the 6-hourly reporting interval.
That is, the 6-hourly data does not capture the estimated winds at landfall.
These landfall designations (as they appear in HURDAT ) are supported by data
and discussion found in the Tropical Cyclone Reports rather than winds given
for the nearest 6-hourly interval.These reports are also found on our website
at